Process for printing of fabrics consisting of synthetic fibers

ABSTRACT

Process for the preparation of printed synthetic fabrics made of polyester and/or acrylic fibers which comprises firstly, in preparing the fabric from two groups of fibers, group (a) consisting of polyester and/or acrylic fibers and group (b) consisting of fibers which are soluble in mineral acids such as cotton and/or viscose and then printing the said fabric with such dyestuffs which are suitable only for synthetic fibers and finally removing by dissolving from the said printed fabric the bottom and/or viscose part, thereby obtaining printed fabric of polyester and/or acrylic fibers only.

United States Patent Dutta et a1. 14 1 Feb. 13, 1973 PROCESS FOR PRINTING 0F FABRICS 3,516,239 6/1970 Fukuda et a1 ..8/l14.6 x

CONSISTING OF SYNTHETIC FIBERS 3,387,916 6/19 8 3,120,423 2/1964 [75] Inventors: Subodh Krishna Dutta;Kr1shnakant 3,122,410 2/1964 Girdharla Shah; Jagdish Ishwarlal setalvad, Ahmedabad, India Primary Examiner-George F. Lesmes [73] Assignee: Ahmedabad Manufacturing & Cal- Ass'stam Exammepq" I Q ico Printing Co. Ltd., Ahmedabad, Atmmey McGlew and Oren l d 57 ABSTRACT 22 F1 d: M h4 1970 1 I 1 l e are Process for the preparation of printed synthetic fabrics [21] Appl. No.: 16,614 made of polyester and/or acrylic fibers which comprises firstly, in preparing the fabric from two groups of fibers, group (a) consisting of polyester and/or (g1 acrylic fibers and g p (b) consisting of fibers which [58] Fie'ld p 8 14 are soluble in mineral acids such as cotton and/or 9 c viscose and then printing the said fabric with such dyestuffs which are suitable only for synthetic fibers [56] References cued and finally removing by dissolving from the said UNITED STATES PATENTS printed fabric the bottom and/or viscose part, thereby obtaining printed fabric of polyester and/or acrylic 2,317,466 4 1943 Kerth e161 ..8/1l4.6 fib only 2,332,738 10/1943 Meade .8/114.6X 2,607,656 8/1952 Ridge ..8/1 14.6 4 Claims, N0 Drawings PROCESS FOR PRINTING OF FABRICS CONSISTING OF SYNTHETIC FIBERS PRIOR ART In the known method of printing of synthetic fabric made out of polyester and/or acrylic fibers, the fabric is first printed with dyestuffs suitable for acrylic and/or polyester fibers and the print is fixed by steaming without or with pressure (depending upon whether a suitable carrier for the dyestuffs is used or not) or by the thermo-setting process at high temperature depending upon the fibers in the fabric and the dyestuffs used.

The printing process hitherto known has not been found to be satisfactory because of the hydrophobic and electrostatic character of the synthetic fibers, as the printed fabric has very little depth of color, has dull appearance and is of an inferior quality of print.

Apart from the aforesaid defects in the printed fabric, it has been found that by the use of roller printing machines, considerable difficulty is experienced in printing, as the adhesion of the dyestuff to the said fabric is not satisfactory, giving contamination of colors and spreading of colors due to pressing by subsequent rollers. By contamination is meant that while printing with multiple colors, there is every possibility of one color getting mixed with another color. This is primarily due to the hydrophobic nature of the synthetic fibers. When printing or such fabric is done on automatic screen printing machines, the gumming on the blanket used in such machines, is difficult also due to hydrophobic character of fibers used and for this reason printing can only be done by using special type of expensive adhesives. Further, there are also difficulties like pressing and marking of prints thus spoiling the quality of printing.

BACKGROUND OF THE INVENTION It has surprisingly been found that if the fabric prepared by mixing or combining fibers of groups (a) and (b) above is printed by dyes suitable only for printing on fabric made of fibers of group (a), then, after printing the said fabric and removing fibers of group (b) by sulphuric acid, the printed fabric has a higher color value, better brilliancy of color and better sharpness of printed design compared to the print obtained by printing directly on fabric made only of synthetic fiber or fibers of-group (a). This excellent result is obtained by the combination of various steps of the process as described hereinabove.

THE INVENTION According to this invention, the process consists in employing the fabric made from two groups of fibers of which group (a) consists of polyester and/or acrylic fibers, the fabric being made with or without metallic or not) or thermosetting at elevated temperature, depending upon the nature of the fibers in the fabric and according to the dyestuffs selected for printing and thereafter, the cotton and/or viscose portion from the printed fabric is dissolved followed by washing, neutralizing and subsequent final washing and drying. The viscose portion of the printed fabric is dissolved by means of sulphuric acid -70 percent w/w (weight by weight) at temperature of 2035C for about I to 2 hours.

Experiments showed that the brightness of the color and its depth improved considerably by the application of the above described process. This surprising result, the applicants are of the view, is possibly due to the fact that when the fabric of synthetic-cum-cotton and/or viscose fibers is printed, the absorbancy of the dye by the mixed fabric is substantially improved due to the presence of cotton/viscose fibers and during the fixing process i.e., (of steaming with or without pressure) or thermosetting process, the dyes which are suitable only for synthetic fibers are transferred from the cotton and/or viscose fibers to the synthetic fibers thereby improving the print properties.

The applicants have found that the cotton and/or viscose portion from the printed fabric can also be removed by other mineral acids or by treating the printed fabric with a solution of oxidizing agents such as potassium or sodium dichromate (2 to 3percent) in sulphuric acid of 2.5 to 5 percent w/w concentration at temperatures between 80 to 90C for about 1 to 2 hours followed by treatment of the fabric with caustic soda solution about 10 percent at C to C for 20 to 30 minutes and subsequently final washing, soaping and drying, but it has been found that the results obtained are not so satisfactory as are obtained by the use of sulphuric acid alone.

The following examples illustrate the invention but these are not to be construed as limitative.

EXAMPLE I Printing Recipe:

1. Disperse Dyestuff 2. Non-ionic surface active 34% (as required) agent 1% 3. Thickner (Gum Meypro-TN);

8% paste Balance to make 100% 4. and water (if required).

After the fabric was printed, it was dried and then baked at I-200C for 1.5 to 2 minutes. The fabric was then rinsed with water, thoroughly dried and then treated with sulphuric acid (68-70 percent w/w) at 25-30C for 1 hour, with material to liquor ratio of I125. The fabric was then rinsed with water, with a little sodium carbonate to neutralize any residual acid on the fabric and then it was soaped with a detergent gms. per liter) and sodium carbonate (2 gms. per liter) at boil for 20 minutes. The fabric was then rinsed with water, dried and finished. The printing was sharp and bright and the color was deep.

The following disperse dyestuffs were used either singly or in suitable combination to produce five or more colored designs:

1. Palanil Blue R C.l. Disperse Blue 56 2. Palanil Yellow 36 Cl Disperse Yellow 64 3. Dispersol Fast Scarlet TR Grains C.l. Disperse Red 158 4. Duranol Direct Black T Grains 5. Foron Yellow Brown S RFL C.l. Disperse Orange 30 6. Palanil Rubin BN C.l. Disperse Red 76 The following polyester-cotton and/or viscose fabrics were also used in the above experiment.

(ii) Fabric having the following particulars:

Warp yarn: 2/65' C.C. (From a blend of 67:33 lyesterctlttong (From a blend of 67:33 polyesterviscose) Weft yarn. 2/60' C.C.

construction 104X60 EXAMPLE 2 A polyester-cotton fabric having weight 65 gms. per sq. metre and count as 58s c.c./58 c.c. (both warp and weft yarns spun from the blend of 67 percent polyester and 33 percent cotton) and construction 68 X 72, with metallic threads (coated with polyester film, with or without suitable color, having specifications as 0.2 mm. width and length 70,000 metres/kg), introduced in warp and/or weft in the repeat ratio of 72 of polyester-cotton yarn to 2 of metallic threads, was printed on a screen printing machine with disperse dyestuffs as in example 1 after giving the fabric proper treatment. The printed fabric after baking, washing and drying was given sulphuric acid treatment as described in example 1. The printing results were very satisfacto- EXAMPLE 3 1. Cationic Dyestuffs 2-4% (as required) 2. Solvent of the type thio diethylene glycol) 3% 3. Acetic Acid (30%) 3% 4. Tartaric acid (50% solution) 3% 5. Suitable carrier 4% 6. Sodium Chlorate (1:2) solution 2% 7. Thickener; Gum Tragacanth paste) balance to make or water (if required) The following cationic dyestuffs were used:

1. Astrazon Blue (FGL) C.l. Basic Blue 22 2. Astrazon Red (F BL) C.l. Basic Red 22 3. Astrazon Golden Yellow GLD C.l. Basic Orange 29 4. Severon Brill. Red 4G C.I. Basic Red 14 5. Sandocryl Black BBL The fabric after printing was dried and steamed for 30 minutes. The fabric was then washed thoroughly with water, dried and then treated with sulphuric acid (66 percent w/w) at 25C (material to liquor ratio at 1:25) for 1 hour and then rinsed with water containing a little sodium carbonate. It was then soaped with an anionic detergent (5 gms. per liter) at 50-60C for 30 minutes, dried and finished in the usual way.

EXAMPLE 4 Acrylic-viscose fabric having specification as described in example 3, with metallic threads (having specifications as described earlier) either in warp or weft or in both in the repeat ratio of 50 acrylic-viscose yarn to 2 of metallic threads, was printed with cationic dyestuffs, dried, steamed and given sulphuric acid treatment as described in example 3. Both in examples 3 and 4 results were found satisfactory.

EXAMPLE 5 A polyester-acrylic-cotton fabric, having wt. per sq. metre as 84 gms. construction 68 X 48 and yarn count as follows:

Warp yarn: 55s c.c. (spun from a blend of 67 percent polyester and 33 percent cotton) Weft yarn: 65s c.c. (spun from a blend of 67 percent polyester and cotton 33 percent) and acrylic polyester gimp yarn prepared from 40s c.c. percent acrylic yarn (1 thread) and 2 threads of 65s c.c. polyester-cotton (67:33) yarn in ratio of 4:2, was desized, scoured, mercerised, heat-set and singed, bleached, dried and printed on an automatic screen printing machine using printing recipe and disperse dyestuffs as in example 1; the print was fixed as before and then the printed fabric was given the acid treatment as described in example 1. The printing results were satisfactory in color depth, brilliancy and sharpness.

In the above example, as the acrylic part of the fabric was small, the dyestuffs for acrylic fibers were not used and the acrylic fibers were kept white.

In the case of polyester-acrylic-cotton and/or viscose fabrics, it is also possible to print selected disperse dyestuffs along side cationic basic dyestuffs, fixing the print by steaming for 30 minutes under pressure and giving sulphuric acid treatment as before to obtain better printing results as described earlier.

What is claimed is:

1. A process for the production of printed synthetic fabrics essentially consisting of polyester fibers and/or acrylic fibers, which comprises:

a. printing a fabric made from a blend of 1. polyester and/or acrylic fibers and 2. cotton and/or viscose fibers with dyestuff suitable only for polyester and/or acrylic fibers,

b. fixing the dyestuff in the conventional manner on the fabric,

c. washing the printed fabric by the conventional method,

d. and thereafter chemically removing the cotton and/or viscose fibers from the printed fabric, whereby a printed fabric consisting only of said polyester and/or acrylic fibers is obtained, having a higher color value, brilliancy of color and better sharpness of printing compared to the conventionally printed synthetic fabric.

2. The process as claimed in claim 1 wherein the removal of said cotton and/or viscose fibers from the printed fabric is carried out with sulphuric acid of a concentration of 60 to percent w/w at a temperature of between 20 to 35C for about 1 to 2 hours with a fabric to liquor ratio of 1 to 25.

3. A process as claimed in claim 2, wherein the fabric is dried after the washing of step (c) and prior to the removal of the cotton and/or viscose fibers of step (d).

4. A process as claimed in claim 3, wherein the blended fabric to be printed also contains metallic threads coated with acid resistant plastic film. 

1. A process for the production of printed synthetic fabrics essentially consisting of polyester fibers and/or acrylic fibers, which comprises: a. printing a fabric made from a blend of
 1. polyester and/or acrylic fibers and
 2. cotton and/or viscose fibers with dyestuff suitable only for polyester and/or acrylic fibers, b. fixing the dyestuff in the conventional manner on the fabric, c. washing the printed fabric by the conventional method, d. and thereafter chemically removing the cotton and/or viscose fibers from the printed fabric, whereby a printed fabric consisting only of said polyester and/or acrylic fibers is obtained, having a higher color value, brilliancy of color and better sharpness of printing compared to the conventionally printed synthetic fabric.
 2. The process as claimed in claim 1 wherein the removal of said cotton and/or viscose fibers from the printed fabric is carried out with sulphuric acid of a concentration of 60 to 70 percent w/w at a temperature of between 20* to 35*C for about 1 to 2 hours with a fabric to liquor ratio of 1 to
 25. 3. A process as claimed in claim 2, wherein the fabric is dried after the washing of step (c) and prior to the removal of the cotton and/or viscose fibers of step (d). 